Whoever came up with this 200' depth parameter for detectors back in the day?
Most of us sweep the dry and wade, possibly snorkel and fan, if we do dive, its probably 25' max for general purpose jump off sites beneath cliffs, bridges, and docks...maybe 50' tops...
The constraints have been amply listed, the only mfg that took advantage of this on a grand scale is Garrett with the ATPro series...I know you Salties need the technology a ML or CZ has to offer, since you are dealing with other issues than us Freshies, still, there would be a fairly large global market for something built along the AT's parameters that gives you what you need to hunt salt..
..(changeable coils and phones)..
My next rig will most likely be the DetectorPro Udub....but again, a guy cant switch coils with that one either...thats the only thing from keeping me from pulling the trigger today...If I decide to dive the aforementioned jump off sites this coming year, I will get one immediately though..
Salt or Fresh, We know that sand/silt is also a huge issue on the shafts...it completely chugs them up and makes collapsing or adjusting them invalid in a very short while...
Well, good luck boys...I hope you find what you are looking for...whoever targets your constraints and builds you what you WANT will make some serious jack...
Mud